title: The novel Nrf2-interacting factor KAP1 regulates susceptibility to oxidative stress by promoting the Nrf2-mediated cytoprotective response.
abstract: The transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) co-ordinately regulates ARE (antioxidant-response element)-mediated induction of cytoprotective genes in response to electrophiles and oxidative stress; however, the molecular mechanism controlling Nrf2-dependent gene expression is not fully understood. To identify factors that regulate Nrf2-dependent transcription, we searched for proteins that interact with the Nrf2-NT (N-terminal Nrf2 transactivation domain) by affinity purification from HeLa nuclear extracts. In the present study, we identified KAP1 [KRAB (Krüppel-associated box)-associated protein 1] as a novel Nrf2-NT-interacting protein. Pull-down analysis confirmed the interaction between KAP1 and Nrf2 in cultured cells and demonstrated that the N-terminal region of KAP1 binds to Nrf2-NT in vitro. Reporter assays showed that KAP1 facilitates Nrf2 transactivation activity in a dose-dependent manner. Furthermore, the induction of the Nrf2-dependent expression of HO-1 (haem oxygenase-1) and NQO1 [NAD(P)H quinone oxidoreductase 1] by DEM (diethyl maleate) was attenuated by KAP1 knockdown in NIH 3T3 fibroblasts. This finding established that KAP1 acts as a positive regulator of Nrf2. Although Nrf2 nuclear accumulation was unaffected by KAP1 knockdown, the ability of Nrf2 to bind to the regulatory region of HO-1 and NQO1 was reduced. Moreover, KAP1 knockdown enhanced the sensitivity of NIH 3T3 cells to tert-butylhydroquinone, H2O2 and diamide. These results support our contention that KAP1 participates in the oxidative stress response by maximizing Nrf2-dependent transcription.
authors.affiliation: Department of Stress Response Science, Center for Advanced Medical Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maruyama
authors.forename: Keizo
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Yukie
authors.initials: Y
authors.lastname: Kawatani
authors.forename: Junsei
authors.initials: J
authors.lastname: Mimura
authors.forename: Tomonori
authors.initials: T
authors.lastname: Hosoya
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Harada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamamato
authors.forename: Ken
authors.initials: K
authors.lastname: Itoh
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019610:Cytoprotection / Q000502:physiology*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000502:physiology*; D041681:NIH 3T3 Cells; D018384:Oxidative Stress / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology; D012097:Repressor Proteins / Q000502:physiology*; D000076183:Tripartite Motif-Containing Protein 28
chemical_list: D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D012097:Repressor Proteins; C101116:TRIM28 protein, human; D000076183:Tripartite Motif-Containing Protein 28